function sayHello() {
  return 'hello word!212sdfe'
}

console.log(``, sayHello())


let num: number = 2;
let num16: number = 0x24245;
let noNum: number = NaN;
let infNum: number = Infinity;

function hello(): void {
  console.log(`hi hello`,)
}

let unable: void = undefined
let unab: void = null

let unable2: undefined = undefined;
unable = null;
let unab3: null = null;
unab = undefined;


let admin: any = 'jdsfo'
admin = 23
admin = false

let anything: any = 'jsdfoe';
console.log(anything.myname)


let voidtt;
voidtt = 'djfoe';
voidtt = 24;
voidtt = false;


let voidtt2 = 'nalefj';

let bl: string | number = 'nalefj';
bl = 23;

// 设置数组类型
let arr = [23, 4, 5, 6];
let arr1: number[] = [23, 42, 14]
// arr1.push('jo') // 报错，类型不一致。

// 使用数组泛型的定义方式
let arr2: Array<number> = [13, 24, 242, 4]
// arr2.push('24dfe') // 报错，类型不一致。

// 接口表示数组类型
interface NumberArray {
  [index: number]: number
}
let arr3: NumberArray = [23, 424, 2424, 24]
// arr3.push('24dfe') // 报错，类型不一致。
